Hi guys, today I decided to write a bit about science, in particular the area of physics, I must say that without doubt there is a theory that promises to have the answer to all our doubts, so this time I want to share this publication about  of the strings theory , but I want to do it explaining in a very general and simple way to understand given the complexity of this topic. One of the most desired dreams of physics is to find a theory that explains, from the formation of atoms to the behavior of stars and even the origin of the universe itself, a theory of everything.
<center>![String_theory.svg.png](https://steemitimages.com/DQmUmed3n7wXQomsGM1n4GnZpKTqMWPCs8XawtaaRJoMCSv/String_theory.svg.png)</center>

>  Legend:
> 1. Matter.
> 2. Molecular structure (atoms).
> 3. Atom (protons, neutrons, electrons).
> 4. Electron.
> 5. Quarks.
> 6. Strings.
> [Source of the image](https://commons.wikimedia.org/wiki/File:String_theory.svg)


Isaac newton was able to describe with his mathematics the attraction movement of objects with mass, be they stars or some fruit like the apple. Later Albert Einstein explained how the phenomenon of gravity happens due to the deformation of space-time, and could explain the behavior of objects that move at speeds close to that of light, something that was beyond the reach of the laws of Newton.

While scientists like [Planck](https://en.wikipedia.org/wiki/Max_Planck), [Bohr](https://en.wikipedia.org/wiki/Niels_Bohr), [Schrödinger](https://en.wikipedia.org/wiki/Erwin_Schr%C3%B6dinger), among others, created quantum mechanics that describes the behavior of particles smaller than the atom, governed more by probabilistic calculations than by the deterministic laws of classical mechanics. 

In the atom there are forces, among them the **Strong:** that holds together protons and neutrons in the nucleus and the **Weak** that is responsible for certain particles to become others. Quantum mechanics can also explain the Electromagnetic force. So on the one hand we have quantum mechanics that explains three of the four fundamental forces and on the other the theory of relativity that explains gravity. Einstein worked the rest of his life on a theory that unified the four forces but could never achieve it, the difficulty was great in essence a theory of everything should explain that everything in the universe is made and why it is so. This question was already asked by philosophers like [Democritus](https://en.wikipedia.org/wiki/Democritus#Atomic_hypothesis) in the fourth century before our era, he thought that if you divide something in two and then one of its parts you cut it again and so as many times as possible should come a time when you would find an object that you could no longer divide, called that hypothetical object "atom" that means "not cuttable".

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<a href="https://imgur.com/FRL8WtD"><img src="https://i.imgur.com/FRL8WtD.png" title="source: imgur.com" /></a>
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[John Dalton](https://en.wikipedia.org/wiki/John_Dalton) until 1804 discovered that these indivisible objects did exist and Niels Bohr explained that it was not an indivisible object but were formed of smaller particles, those particles are protons, neutrons and electrons and their quantity determines if it is an atom of oxygen or fluorine.
[source of image](https://pixabay.com/es/litio-atom-aislado-at%C3%B3mico-f%C3%ADsica-2784853/)

Then, following this, we ask ourselves, _what are these subatomic particles made of?_

The standard model tells us that they are made of other elementary particles, [Leptons](https://en.wikipedia.org/wiki/Lepton), [Quarks](https://en.wikipedia.org/wiki/Quark) and also [Bosons](https://en.wikipedia.org/wiki/Boson), although the standard model is consistent with the experiments has left several questions unresolved, for example.

![502px-Standard_Model_of_Elementary_Particles.svg.png](https://steemitimages.com/DQmQ8aSbJe63D7t2xHCRwp2V3P9PhyEJzDT8Jvcm5HQB5wB/502px-Standard_Model_of_Elementary_Particles.svg.png) 
[Source](https://commons.wikimedia.org/wiki/File:Standard_Model_of_Elementary_Particles.svg)

* Why do forces have certain arbitrary parameters called "constant" and not others?
But above all ...

*  Where does gravity come from?

It is in this context that string theory arises, in fact they are five theories or five different approaches but basically postulates that subatomic particles are not dots without dimension as conceived by the standard model, but strings of a dimension, their measurement the length of Planck which is the smallest possible distance, in other words, the pixel of the universe. It happens that these strings vibrate and move following different frequencies and patterns, determined by the multidimensional space in which they move; The way in which they vibrate defines what type of particle they form. Just as the vibration of a guitar string defines which defines which notes you listen to.

Now, multidimensional space? ... to be mathematically coherent string theory requires that the strings move, not in three or four but in 10 different dimensions.

* _But not that space - time had four dimensions, from which the other six come out?_

One explanation is that these extra dimensions are microscopic, they are somehow located and hidden in the smallest possible scale, the strings would exist in this multidimensional space called [the Calabi - Yau space](http://mathworld.wolfram.com/Calabi-YauSpace.html). If these extra dimensions are real, it would explain why we observe that certain particles appear and disappear without us knowing where they come from or where they are going. The strings would be made of pure energy, therefore matter is made of energy which is consistent with the relativistic equation that energy is equal to mass multiplied by the speed of light squared (E=mc2).

<center>![460px-Calabi_yau.jpg](https://steemitimages.com/DQmbWa4vKDqjPaTRLECfAtVrMZFc9id3NgrLfwdFtT3Uaxs/460px-Calabi_yau.jpg)</center>
<center>[A cross section of a quintic Calabi–Yau manifold](https://commons.wikimedia.org/wiki/File:Calabi_yau.jpg)</center>

Certain strings that were closed would be the desired ["gravitons"](https://en.wikipedia.org/wiki/Graviton), the particles that would mediate gravity but this part of the theory is still very problematic. Another problem with string theory is that if it is true it describes our universe and its laws, but also millions of other laws and other constants that do not exist. Those who defend it affirm that this is not a problem since they are laws and constants of other universes, but that could indicate that our universe arose from the collision of other universes or the division of a universe in two.

### More Information.

* https://sciencing.com/difference-between-quarks-leptons-8076741.html

* https://physicsworld.com/a/string-theory-calculations-describe-birth-of-the-universe/

### If you liked what you just read do not forget to follow me and support me @jlmol7
> The images used in this article can be reused according to your copyright.

### References.

* http://www.superstringtheory.com/

* https://www.britannica.com/science/string-theory 

* https://en.wikipedia.org/wiki/Standard_Model

* http://www.wisegeek.com/what-is-multi-dimensional-space.htm